Gas turbine combustion engines with can-annular combustors require structures to transport the gases coming from the combustors to respective circumferential portions of the first row of turbine blades, hereafter referred to simply as the first row of turbine blades. These structures must orient the flow of the gases so that the flow contacts the first row of turbine blades at the proper angle, to produce optimal rotation of the turbine blades. Conventional structures include a transition, a vane, and seals. The transition transports the gases to the proper axial location and directs the gases into the vanes, which orient the gas flow circumferentially as required and deliver the gas flow to the first row of turbine blades. The seals are used in between the components to prevent cold air leakage into the hot gas path.
Configurations of this nature reduce the amount of expansion potential present in the gas flow as the flow travels toward the first row of turbine blades, and inherently require substantial cooling. Gas flow expansion potential is lost through turbulence created in the flow as the flow transitions from one component to the next, and gas energy is reduced from cold air leakage into the hot gas path. Cold air leakage into the hot gas path through seals increases as seals wear due to vibration and ablation Significant energy is also lost when the flow is redirected by the vanes. These configurations thus create inefficiencies in the flow which reduce the ability of the gas flow to impart rotation to the first row of turbine blades.
In addition, manufacture of the cooled components can be expensive and complicated due to the cooling structures, exacting tolerance requirements, and required shapes. Additionally, the cooled components require a supply of cooling fluid from the engine, with an associated expenditure of energy to produce the flow of cooling fluid.